1. Technical Field of the Invention
This invention relates to a system and method for the efficient dimensioning of a telecommunications network, and more particularly, to a technique for dimensioning defined virtual paths on a constrained physical network using the Entropy Rate Function as a blocking measure.
2. Description of Related Art
Telephone instruments and other communications devices located in a localized geographic area are conventionally connected with one another by means of switching equipment referred to as local exchanges. Local exchanges, in turn, are interconnected by trunk exchanges. Telephone/data instruments located in geographic areas separated from one another and connected to different local exchanges communicate with one another via a complex grouping of local and trunk exchanges linked together into a telecommunications network. A telecommunication network thus comprises a plurality of interconnected network elements, such as local exchanges, trunk exchanges, mobile radio exchanges, long distance exchanges and combinations thereof. At each network level, traffic from one network element, such as an exchange, to another network element can take various routes that pass through different exchanges.
Efficient network traffic management of the communication facilities within a network requires that a sufficient number of circuits be available to handle the traffic requirements of each destination without exaggerated congestion on last-choice traffic routes. It also requires that the network congestion be as even as possible on all last-choice routes and that unused capacity within the routes which are actually provided be minimized in order to insure efficient utilization of resources. In addition, the telephone company which operates a network has a limited budget and consequently must get as much efficiency as possible out of the existing resources in each network.
In the past, traffic management within a communications network has included procedures for periodically surveying the traffic patterns within the network and changing the configuration of circuits and routes to increase the traffic handling efficiently. In addition, more routes and circuits may be added to a network in anticipation of high call densities to a particular location or a particular region and to local events within that region. Conventional network management systems are also capable of changing the relative distribution of traffic loads between selected routes within the network in order to efficiently maximize the utilization of the network without excessive degradation in the quality of service (QoS). However, conventional traffic network management systems and procedures have generally strived to increase the availability of circuits and routes within a network to handle individual traffic demands rather than to reconfigure a network by redimensioning the routes and circuits within it at a higher level of abstraction so as to maximize the overall efficiency of the network.
In addition to the inherent need to maximize the efficiency of managing physical network resources within a telecommunications system, the growth in information and communications technologies in recent years has created a wealth of new economic opportunities and managerial challenges. Vendors providing telecommunications services are continually faced with new customer demands. Providing ordinary voice communications through a telecommunications network is no longer enough. Today's users want the ability to transmit not just voice signals, but also data, audio, video and multimedia signals in both real time as well as through packet switching networks. Asynchronous Transfer Mode (ATM) technology is acquiring increasing significance due to its enhanced ability to provide broadband telecommunications facilities.
A principal feature of ATM technology is its flexibility in the utilization of network resources. One possible approach to exploit this flexibility is to partition the physical network resources, either completely or partially, into logically defined resources. For example, by partitioning a physical network into a plurality of virtual networks, the operation, maintenance and management of a physical network can be substantially simplified. By this procedure, the task of analyzing and solving the traffic routing problem for each call over an entire physical network can be reduced to the considerably simpler routing problem on each virtual network. Each of the individual virtual networks have less complexity than the entire physical network as a whole, making the solution of the traffic routing problem easier.
Partitioning of physical resources can also be necessitated by the existence of different traffic types, different classes of service or varying traffic demands within leased networks. Instead of providing a separate physical network for each customer application, a service provider can set up a number of virtual networks defined on top of a single common ATM physical infrastructure.
This new flexibility in the configuration of virtual network structures demands efficient dimensioning tools, methods and algorithms. Since the nature of the telecommunications services that will be offered in the future are hard to predict, any dimensioning method that is used to manage the configuration of virtual network resources must be capable of dealing with all types of broadband traffic. If the configuration of a virtual network has to be frequently revised in order to adapt to changes in the pattern of offered traffic, then the computational efficiency of the network redimensioning and configuration control system also needs to be high. An algorithm selected for performing network redimensioning and reconfiguring a network should perform its calculations in a time period that is much shorter than the time duration of each virtual network.
Many existing dimensioning techniques are excluded by the requirement that the dimensioning technique be capable of modeling a general traffic distribution. Most commonly used dimensioning methods are not capable of handling general traffic models because of limitations arising from the use of the Erlang blocking measure. The method and system of the present invention overcomes these disadvantages.